Replacement of underground pipes

ABSTRACT

This document discusses, among other things, devices, apparatuses, and methods for the replacement of existing underground pipes. In general, an apparatus comprises a body, including a receiving portion, and a breaking assembly adapted to be positioned within the receiving portion and detachably coupled to the body. In one example, the body and the breaking assembly are adapted, when coupled, to split the existing underground pipe when pulled therethrough using one or more cutting wheels. In varying examples, each cutting wheel radially protrudes out of a breaking assembly housing an increasing amount along a length of the apparatus allowing for a clean, progressive cut of the existing pipe. In another example, the body and the breaking assembly are adapted, when coupled, to burst the existing pipe when pulled therethrough. Advantageously, the present devices, apparatuses, and methods may provide replacement of underground pipes requiring minimal excavation and making economical use of parts.

CROSS REFERENCE

This patent application claims the benefit of priority, under 35 U.S.C.Section 119(e), to U.S. Provisional Patent Application Ser. No.60/672,267, filed on Apr. 18, 2005, which is incorporated herein byreference.

TECHNICAL FIELD

This patent document pertains generally to devices, apparatuses, andmethods for pipe replacement, and more particularly, but not by way oflimitation, to devices, apparatuses, and methods for the replacement ofunderground pipes.

BACKGROUND

Underground pipes are used for, among other things, connecting homes andcreating networks for utilities such as sewer, water, gas, electric,telephone, etc. As underground pipes age, they are subject to inevitabledeterioration and wear. As a result, underground pipes need to bereplaced from time-to-time.

One method for replacing existing underground pipe with replacement pipeis to excavate the entire length of the existing pipe, remove it andplace new replacement pipe into the excavation. Drawbacks of such“excavation” method of replacing existing underground pipe are numerous.For example, excavation of existing pipe can be expensive,time-consuming, labor-intensive, and may result in damage to the areasurrounding the excavation. In many instances, a main portion ofunderground pipes lie beneath driveways, buildings, lawns, or gardens,and property owners are often concerned about any damage that may resultthereto. In addition, excavation is often made difficult by the presenceof other underground utilities.

A technique known as “pipe bursting” may be one way to replaceunderground pipe without the need to dig up the pipe to be replaced. Inpipe bursting, an expander, which is also sometimes referred to as a“mole,” is pulled by a cable, chain, or other similar means through theexisting pipe while it is still underground. The body of the expander istypically slightly larger than an inner diameter of the existing pipe.As the expander is pulled, it is designed to break or “burst” theexisting underground pipe into many remnants, and at the same timeexpand the remnants into the surrounding soil. The expansion of the oldpipe allows the expander to pull a replacement pipe into place.

A technique known as “pipe splitting” may be another way to replaceunderground pipe without the need to dig up the pipe to be replaced. Inpipe splitting, a pipe splitter is pulled by a cable through theexisting pipe while it is still underground. A first portion of the pipesplitter is typically slightly smaller in diameter than the innerdiameter of the pipe to be replaced. As the pipe splitter is pulled, itis designed to split the existing pipe, and at the same time expand thesplit pipe into the surrounding soil. The expansion of the split pipeallows the pipe splitter to simultaneously pull a replacement pipe intoplace.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsdescribe similar components throughout the several views. The drawingsillustrate generally, by way of example, but not by way of limitation,various embodiments discussed in the present document.

FIG. 1 is a side view of one embodiment of the present apparatus in atrenchless pipe replacement operation.

FIG. 2A is an isometric view illustrating one embodiment of the presentapparatus.

FIG. 2B is an isometric view illustrating another embodiment of thepresent apparatus.

FIG. 3 is an isometric view illustrating a device of one embodiment ofthe present apparatus.

FIG. 4A is an isometric view illustrating an assembly of one embodimentof the present apparatus.

FIG. 4B is an isometric view illustrating one element of the assembly ofFIG. 4A.

FIG. 4C is an isometric view illustrating another element of theassembly of FIG. 4A.

FIG. 4D is a side view illustrating an option for an element of theassembly of FIG. 4A.

FIG. 4E is a side view illustrating another option for an element of theassembly of FIG. 4A.

FIG. 5A is a side view illustrating one portion of a mounting system ofan assembly according to one embodiment of the present apparatus.

FIG. 5B is a side view illustrating another portion of a mounting systemof an assembly according to one embodiment of the present apparatus.

FIG. 6 is an isometric view illustrating another device of oneembodiment of the present apparatus.

FIG. 7 is a flow chart illustrating a method of replacing existingunderground pipes of various sizes according to one example of thepresent method.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of this detailed description.The drawings show, by way of illustration, specific embodiments in whichthe present devices, apparatuses, and methods may be practiced. Theseembodiments, which are also referred to herein as “examples, ” aredescribed in enough detail to enable those skilled in the art topractice the present devices, apparatuses, and methods. The embodimentsmay be combined, other embodiments may be utilized, or structural orlogical changes may be made without departing from the scope of thepresent devices, apparatuses, and methods. It is also to be understoodthat the various embodiments of the present devices, apparatuses, andmethods, although different, are not necessarily mutually exclusive. Forexample, a particular feature, structure or characteristic described inone embodiment may be included within other embodiments. The followingdetailed description is, therefore, not to be taken in a limiting sense,and the scope of the present devices, apparatuses, and methods aredefined by the appended claims and their legal equivalents.

In this document: the terms “a” or “an” are used to include one or morethan one; the term “or” is used to refer to a nonexclusive or, unlessotherwise indicated; and the term “cable” is used to include metalcables, wire rope, or other lengths of material of suitable strength topull the present devices or apparatuses through a section of existingunderground pipe or execute the present methods as described below andas defined by the appended claims.

INTRODUCTION

The following Detailed Description will discuss devices, apparatuses,and methods that provide replacement of underground pipe without theneed for (extensive) excavation. Although the embodiments discussedherein refer (in large part) to pipe splitting devices; pipe burstingdevices utilizing similar concepts (e.g., a detachable breakingassembly, a plurality of body sizes, and progressively increasingbreaking assembly elements along a longitudinal length of a breakingassembly housing) are also contemplated.

Advantageously, the present devices, apparatuses, and methods in oneembodiment provide a pipe splitter allowing for a clean, predicable cutof an existing underground pipe and an increase in the speed anddecrease in the power needed to pull the pipe splitter therethrough.Further, the present devices, apparatuses, and methods provide a pipesplitter having an economically favorable (interchangeable) design.

EXAMPLES

FIG. 1 is a side view illustrating utilization of one embodiment of anapparatus 102 in a trenchless pipe replacement operation 100. Asdepicted in FIG. 1, an existing pipe 104 that is being replaced isdisposed beneath the ground level surface 106. A first hole 108 may bebeen dug to reveal a first end 110 of existing pipe 104 and a secondhole 122 may be dug to reveal a second end 120 of existing pipe 104.Apparatus 102 may be inserted within the first end 110 of existing pipe104. Apparatus 102 generally includes a body 112 (FIGS. 2A-2B) and abreaking assembly 114 (FIGS. 2A-2B). A description of apparatus 102 ispresented in greater detail below. A length of replacement pipe 116 isremovably engaged to a trailing end of apparatus 102.

A cable 118 is passed through the pipe 104 and attached with a leadingend of apparatus 102. In one example, cable 118 is attached to theleading end of apparatus 102 via a pinned arrangement. In anotherexample, cable 118 is attached to the leading end of apparatus 102 via ahooked arrangement. Other connections between cable 118 and the leadingend of apparatus 102 may also be used and are within the scope of thepresent devices, apparatuses, and methods. Cable 118 may be utilized topull apparatus 102 through existing pipe 104, breaking and enlarging thepipe 104 as it is pulled therethrough. In one example, breaking pipe 104includes splitting the pipe 104 along substantially one line of cut. Inanother example, breaking pipe 104 includes bursting the pipe 104 intomany pieces. Replacement pipe 116 may be simultaneously pulled behindapparatus 102, such that when apparatus 102 has been pulled entirelythrough existing pipe 104, replacement pipe 116 will reside within thesplit or broken pipe 104 to functionally replace it.

Advantageously, the trenchless replacement operation 100 may be easy toset up and operate (e.g., dig holes at each end of existing pipe 104,attach cable to appropriately-sized apparatus 102 (including body 112and breaking assembly 114), attach replacement pipe to apparatus 102,and pull apparatus 102 through pipe 104). As a result, minimal crews maybreak and replace substantial lengths and various types of existing pipe104 in a short amount of time. In one example, apparatus 102 replacespipes 104 made of metal (including corrugated structures) or polymers.Moreover, because the operation is essentially trenchless (e.g., no needto excavate along the entire length of pipe 104 to be replaced),considerable lengths of trench work and costly restoration are avoided.

FIGS. 2A-2B are isometric views illustrating two embodiments ofapparatus 102. As discussed above, apparatus 102 may be used for thetrenchless replacement of an existing underground pipe 104. In bothillustrative embodiments, apparatus 102 includes a body 112 and abreaking assembly 114. In varying examples, body 112 includes areceiving portion 124, such as a longitudinally-extending receivingportion. The breaking assembly 114 may be positioned within thereceiving portion 124 and coupled to body 112. In one example, breakingassembly 114 is detachably coupled to body 112, such as by bolt and nut126. Other attachment means between breaking assembly 114 and body 112may be used without departing from the scope of the present devices,apparatuses, and methods. When coupled, body 112 and breaking assembly114 are adapted to break existing underground pipe 104 when pulledtherethrough.

It is often important in many trenchless pipe replacement operations 100for body 112 to be substantially similar in size to an inner diameter ofexisting pipe 104 (notably, a similar size between body 112 and theinner diameter of existing pipe 104 may ensure that breaking assembly114 has adequate supporting force to produce a break). It follows then,for different sized existing pipes 104, different sized apparatuses 102may be needed. Advantageously, body 112 and breaking assembly 114 areadapted to be detachably coupled. As a result, breaking assembly 114 maybe used interchangeably with different sized bodies 112 to formapparatus 102. One advantage of such an arrangement is that rather thanhaving to purchase many different sized apparatuses 102 (e.g.,non-detachable body 112, breaking assembly 114 combinations), apurchaser may purchase a single breaking assembly 114 and a plurality ofdifferent sized bodies 112, which are cheaper to manufacture (and thuspurchase) than whole combinations (e.g., breaking assembly 114 and body112). As shown, breaking assembly 114, which is coupled to body 112 inthe illustrative FIG. 2A, may also be coupled to smaller (diameter) body112′ of FIG. 2B.

In some examples of FIG. 2A, body 112 and breaking assembly 114 areadapted, when coupled, to split existing pipe 104 when pulledtherethrough using, at least in part, one or more cutting wheels 128 a,128 b, 128 c, . . . , 128 n. In this example, apparatus 102,specifically breaking assembly 114, includes four cutting wheels;however, the present devices, apparatuses, and methods are not solimited. In other examples, breaking assembly 114 includes five or morecutting wheels. Still, in other examples, breaking assembly 114 includesfewer than four cutting wheels.

In varying examples, each of the one or more cutting wheels 128 a, 128b, 128 c, . . . , 128 n are adapted to rotate relative to the breakingassembly housing 130. In one example, each cutting wheel 128 a, 128 b,128 c, . . . , 128 n communicates with a bearing, which may be locatedwithin the wheel itself (FIG. 5B). Other configurations allowing eachcutting wheel 128 a, 128 b, 128 c, . . . , 128 n to rotate relative tothe breaking assembly housing 130 may also be used without departingfrom the scope of the present devices, apparatuses, and methods.

In some examples, each of the one or more cutting wheels 128 a, 128 b,128 c, . . . , 128 n includes a sharp cutting edge without any supportportion or shoulder (e.g., portion to limit an aggressiveness of thesplit made by the cutting wheel, see FIG. 4C). In some examples, a size(e.g., diameter) of each cutting wheel 128 a, 128 b, 128 c, . . . , 128n increases or stays the same along a longitudinal length of apparatus102. In this example, cutting wheels 128 a, 128 b, 128 c, . . . , 128 nare equally sized and as a result of being eccentrically mounted (FIGS.5A-5B), radially protrude out of breaking assembly housing 130 anincreasing amount (184, 186, 188) along the longitudinal length ofapparatus 102.

In some examples, breaking assembly 114 includes at least one scoringwheel 132 (FIG. 4B). In this example, one scoring wheel 132 ispositioned to groove an inner surface of existing pipe 104 in advance ofcutting wheels 128 a, 128 b, 128 c, . . . , 128 n. In one example,scoring wheel 132 includes a sharp cutting edge and a support portion.In one method of operation, the scoring wheel 132 functions to begin asplit in the inner surface of existing pipe 104, without being tooaggressive (e.g., limited by the support portion) about the split in thefirst wheel. In this example, scoring wheel 132 radially protrudes outof breaking assembly housing 130 less than cutting wheels 128 a, 128 b,128 c, . . . , 128 n (182). In other examples, breaking assembly 114includes multiple scoring wheels 132. In some examples, breakingassembly 114 includes another cutting wheel 128, as described above, inthe place of scoring wheel 132. In varying examples, a diameter ormounting of each wheel (e.g., cutting wheel 128 or scoring wheel 132),and the presence or absence of a support portion, as in scoring wheel132, determine an amount of splitting that each wheel performs.

By selecting a combination of wheels, including scoring wheel(s) 132 andcutting wheel(s) 128, and various diameters or mountings of such wheels,a progressive splitting operation may be performed resulting in a lowerand more consistent pulling force requirement to advance apparatus 102through existing underground pipe 104. Other elements, such as fins,expanders, etc. are further added to the apparatus 102 in otherembodiments.

As shown in FIG. 2A, apparatus 102 further includes a leading pullingdevice 134. In some examples, leading pulling device 134 is coupled to afirst end 138 of one or both of: body 112 and breaking assembly housing130. In this example, leading pulling device 134 is detachably coupledto a first end 138 of breaking assembly housing 130. As shown in thisexample, leading pulling device 134 includes a generally tapered noseportion having bore 142 formed therethrough for releasably engagingcable 118, which is adapted to pull apparatus 102 through existing pipe104.

Apparatus 102 may also include a trailing pulling device 136. In someexamples, trailing pulling device 136 is coupled to a second end 140 ofone or both of: body 112 and breaking assembly housing 130. In thisexample, trailing pulling device 136 is detachably coupled to a secondend 140 of breaking assembly housing 130. As shown in this example,trailing pulling device 136 includes a generally tapered nose portionhaving a bore 144 formed therethrough for releasably attaching toreplacement pipe 116 to simultaneously pull replacement pipe 116 intoplace as apparatus 102 is pulled through existing underground pipe 104by cable 118.

In some examples, a size and a shape of leading pulling device 134 andtrailing pulling device 136 and a location of bores 142, 144 relate to asize of body 112, such that apparatus 102 is pulled through existingunderground pipe 104 from an apparatus center (e.g., geometric center).As discussed above, body 112′ shown in FIG. 2B is smaller in diameter172 than body 112 shown in FIG. 2A having diameter 170. Thus, in theillustrative examples of FIGS. 2A-2B, leading pulling device 134 of FIG.2A differs in size and shape from leading pulling device 134′ of FIG.2B. Similarly, trailing pulling device 136 of FIG. 2A differs in sizeand shape from trailing pulling device 136′ of FIG. 2B. Moreover, thelocation of bores 142, 144 shown in FIG. 2A differ from the location ofbores 142′, 144′ shown in FIG. 2B.

In some examples, such as in FIG. 2A, a cross bar 146 is coupled toleading pulling device 134 on a cross bar first end 138 and is coupledto trailing pulling device 136 on a cross bar second end 140, such asfor larger pulling device 134, 136 sizes. In one example, cross bar 146may be used to provide additional support to pulling devices (e.g., 134,136) having a height 180 which is greater than a height 178 of breakingassembly housing 130. Cross bar 146 may also play a role in ensuringapparatus 102 is pulled through existing underground pipe 104 from itsgeometric center.

In varying examples, apparatus 102 includes at least one skid structure148 coupled to an outer surface of body 112. In the illustrative exampleof FIG. 2A, a plurality of skid structures 148 are coupled to the outersurface of body 112. Skid structures 148 may be used to contact an innersurface of existing underground pipe 104 and advantageously areinexpensive to manufacture. In some examples, skid structures 148 areformed from a material that provides a low coefficient of friction withexisting pipe 104. Coefficient of friction, which is also sometimesreferred to as “frictional coefficient,” or simply as “frictioncoefficient,” is a scalar value used to calculate a force of frictionbetween two bodies. It is usually between 0 and 1. The coefficient offriction depends on the materials used. A low coefficient of frictionindicates that materials rub together easily. Advantageously, skidstructures 148 may be composed of a material having a low coefficient offriction with a material of existing pipe 104 to be split or burst,requiring less effort (e.g., a lower pulling force requirement) to moveapparatus 102 through existing pipe 104. In some examples, skidstructures 148 are formed from a material having a hardness greater thana hardness of the material used in existing pipe 104. Advantageously,when skid structures 148 possess a greater hardness than existing pipe104, wear and deformation may be minimized as apparatus 102 is pulledthrough pipe 104.

A size (e.g., a width 174 or depth 176) of skid structures 148 may vary.In one example, skid structures 148 of FIG. 2A have a larger width 174and smaller depth 176 than the skid structures 148′ of FIG. 2B. Inanother example, a depth 176 of skid structures 148 gradually increasesalong a longitudinal length of body 112. The increase in depth 146 ofskid structures 148 may maintain constant localized pipe tension withinthe pipe 104 in the vicinity of the location of the break (e.g., splitor burst) as apparatus 102 is pulled therethrough. For example, as pipe104 is progressively split, the circumferential integrity of theexisting pipe decreases. By increasing the effective size (e.g.,diameter) of apparatus 102 along a longitudinal length, added tightnessbetween apparatus 102 and existing pipe 104 is imported such thatcutting wheels 128 a, 128 b, 128 c, . . . , 128 n may more easilyperform their splitting function.

FIG. 3 is an isometric view illustrating a portion of body 112 (ofapparatus 102). As discussed above, body 112 may advantageously becoupled in a detachable manner to breaking assembly 114. In this way, asingle breaking assembly 114 may be attached to a plurality of differentsized bodies 112. In one example, a size of body 112 is indicated by adiameter 150 of the body 112. Coupled to an outer surface of the portionof body 112 are a plurality of skid structures 148. In some examples, asis shown in FIG. 3, body 112 includes a shell structure having at leastone internal support member 152. The shell structure may be formed by acylindrical portion 154 within body 112. Advantageously, the shellstructure reduces weight associated with apparatus 102 and reducesmaterial costs associated with manufacturing apparatus 102. Internalsupport member 152 provides the shell structure with integrity which isneeded as apparatus 102 is pulled through existing underground pipe 104.

FIG. 4A is an isometric view illustrating breaking assembly 114. In thisexample, breaking assembly 114 is shown detached from body 112 andincludes a plurality of openings for use in attachment to body 112(e.g., hole 113) and for attachment to leading and trailing pullingdevices 134 (e.g., holes 135) and 136 (e.g., holes 137), respectively.In this example, a bolt may be inserted through holes 113, 135, and 137on a first side of breaking assembly 114 and tightened on a second sideof breaking assembly 114. In this example, breaking assembly 114includes four cutting wheels 128 a, 128 b, 128 c, . . . , 128 n and onescoring wheel 132 to split existing underground pipe 104; however, thepresent devices, apparatuses, and methods are not so limited. Asdiscussed above, the number, size, or position (e.g., height of wheelsprotruding out of cutting assembly housing 130) of each cutting wheel128 and scoring wheel 132 may vary. In one example, the number, size, orposition of cutting wheels 128 and scoring wheels 132 may depend on acomposition material of pipe 104 to be split or the available pullingforce to pull apparatus 102 through pipe 104. In another examples, atleast one scoring wheel 132 and one or more cutting wheels 128 a, 128 b,128 c, . . . , 128 n (increasing in protruding height along alongitudinal length of apparatus 102) progressively split pipe 104.Progressive splitting may advantageously provide a more predictablesplit with less tearing of existing underground pipe 104. With apredictable split, a constant or near-constant pulling force requirementmay be calculated and provided for (e.g., equipment, equipmentsettings). A constant pulling force may advantageously lessen the needfor excess pulling force capabilities at a work site.

FIGS. 4B and 4C provide respective examples of a scoring wheel's 132 anda cutting wheel's 128 isometric profile. The illustrative scoring wheel132 of FIG. 4B includes a sharp cutting edge 156 and a support portion158. In one method of operation, the scoring wheel 132 functions tobegin to split (e.g., groove) an inner surface of existing pipe 104 viacutting edge 156, without being too aggressive (limited by supportportion 158). In one example, a plurality of cutting wheels 128 a, 128b, 128 c, . . . , 128 n successively follow and deepen the grooveproduced by scoring wheel 132. The illustrative cutting wheel 128 ofFIG. 4C includes sharp cutting edge 160 without any support portion orshoulder to limit an aggressiveness of split made by cutting wheel 128.

A number of options exists for each scoring 132 and cutting 128 wheel.In one example, each scoring 132 and cutting 128 wheel is formed of ahardened steel. In some examples, each scoring 132 and cutting 128 wheelare removably engagable with breaking assembly housing 130, such thatthey may easily be replaced when it is necessary to do so (e.g., due todulling) without having to purchase a new breaking assembly 114.

FIGS. 4D and 4E provide two exemplary side profiles of the periphery ofone or more scoring 132 or cutting 128 wheels. In one example, at leastone of the one or more cutting wheels 128 a, 128 b, 128 c, . . . , 128 nmay include one or more notches 200 at its periphery. In anotherexample, at least one scoring wheel 132 includes one or more notches 200at its periphery. Advantageously, the notches 200 may provide forgreater wheel (e.g., scoring wheel 132, cutting wheel 128) rotation asapparatus 102 is pulled through existing underground pipe 104 and mayaccordingly lower friction between the wheels 132, 128 and existingunderground pipe 104 as the pipe 104 is split. Further, the notches 200may provide increased cutting ability of existing underground pipe 104.Moreover, use of notches 200 may reduce tearing of pipe 104 which mayoccur if the cutting or scoring wheels become jammed with the pipe 104as apparatus 102 is pulled therethrough. In one example, lower frictionprovided by designs disclosed herein provide the ability to splitcorrugated steel pipe that previously was not splittable by trenchlessmethods. Other sizes, shapes, and configurations of notches 200 at theperiphery of cutting wheels 128 a, 128 b, 128 c, . . . , 128 n orscoring wheel 132 are also within the scope of the present devices,apparatuses, and methods. In the example of FIG. 4D, the notches 200made in the periphery of the cutting wheels 128 a, 128 b, 128 c, . . . ,128 n or scoring wheel 132 are similar size and shape. In the example ofFIG. 4E, the notches 200 made in the periphery of cutting wheels 128 a,128 b, 128 c, . . . , 128 n or scoring wheel, instead of all being thesame size, are of two different sizes.

FIGS. 5A-5B illustrate portions of a mounting system to mount cuttingwheels 128 a, 128 b, 128 c, . . . , 128 n or scoring wheel 132 to thebreaking assembly housing 130. FIG. 5A provides one example of a innerfacing side 204 of breaking assembly housing 130. As shown, inner facingside 204 includes a plurality of geometric mounting protrusions 206,such as triangles, which protrude outward from the inner facing side204. In this example, four geometric mounting protrusions 206 are shown;however, the present devices, apparatuses, and methods are not solimited. In one example, less than four geometric mounting protrusions206 are included. In another example, more than four geometric mountingprotrusions 206 are included. To each geometric mounting protrusion 206,a cutting 128 or scoring 132 wheel may be eccentrically mounted.

FIG. 5B provides one example of a cutting wheel 128 or scoring wheel 132that is configured to eccentrically mount to breaking assembly housing130 via geometric mounting protrusion 206. In this example, each cuttingwheel 128 or scoring wheel 132 includes a geometrically shaped cavity210 identical in shape and size with the geometric mounting protrusion206. Therefore, the geometric cavity 210 of each cutting 128 or scoring132 wheel may be matably coupled with each geometric mounting protrusion206. Although the above discusses an embodiment where inner facing side204 includes protrusions 206 and each cutting 128 and scoring 132 wheelincludes cavity 210, the present devices, apparatuses, and methods arenot so limited. In another example, inner facing side 104 includescavities and each cutting 128 and scoring 132 wheel includes aprotrusion.

As shown in FIG. 5B, the geometrically shaped cavity includes edges(e.g., apexes) located at various distances from wheel edge 212. In thisexample, the apexes of cavity 210 are distanced from wheel edge 212 bydistances A, B, and C. In this example, distance A is greater thandistance B, and distance B is greater than distance C. Due to the factthat cavity 210 apex's are located at various distances from wheel edge212, mounting orientation of the wheels 128, 132 to the protrusions 206will determine an amount that each cutting wheel 128 or scoring wheel132 radially protrudes out of breaking assembly housing 130. As anexample, if greatest distanced (from wheel edge 212) apex (apexassociated with distance A) of wheel 128 or 132 is mated to the top apexof geometric protrusion 206, such wheel's periphery will extend out ofthe breaking assembly housing more than if lesser distanced (from wheeledge 212) apex (apex associated with distance B) of wheel 128 or 132were mated with the top apex of protrusion 206. Similarly, if leastdistanced (from wheel edge 212) apex (apex associated with distance C)of wheel 128 or 132 is mated with the top apex of geometric protrusion206, such wheel's periphery will extend out of the breaking assemblyhousing less than if the apex associated with distance A or B were matedwith the top apex of protrusion 206. By sequentially using the cavityapex associated with distance C, the cavity apex associated withdistance B, and the cavity apex associated with distance A, breakingassembly 114 may be configured such that each cutting 128 or scoringwheel 132 protrudes out of the breaking assembly housing 130 anincreasing amount along a longitudinal length of breaking assemblyhousing 130.

In one example, each wheel 128 or 132 includes a bearing 214 allowingthe wheel to rotate relative to the breaking assembly housing 130 asapparatus 102 is pulled through existing underground pipe 104. Othereccentric design configurations allowing each cutting wheel 128 a, 128b, 128 c, . . . , 128 n or scoring wheel 132 to rotate relative tobreaking assembly housing 130 and progressively increase in height mayalso be used without departing from the scope of the present subjectdevices, apparatuses, and methods.

FIG. 6 is an isometric view illustrating a leading pulling device 134detachably couplable to apparatus 102. In one example, leading pullingdevice 134 may be coupled to breaking assembly 114 via holes 135′. Inthis example, holes 135′ of leading pulling device align with holes 135of breaking assembly 114, specifically breaking assembly housing 130,and are secured by a plurality of bolts and nuts. In some examples,leading pulling device 134 includes a generally tapered nose portionhaving bore 142 formed therethrough for releasably engaging a cable 118,which is adapted to pull apparatus 102 through existing underground pipe104. In this example, leading pulling device 134 further includes holes147 to attach a cross bar 146 as described in greater detail above. Invarying examples, leading pulling device is sized and shaped (e.g., thelarger the existing pipe, the larger the leading pulling device) to pullapparatus 102 from an apparatus center. The apparatus center may be thegeometric center of apparatus 102. Advantageously, pulling from theapparatus center allows apparatus 102 to proceed in a straight coursethrough existing underground pipe 104.

FIG. 7 is a flow chart illustrating one method of replacing existingunderground pipes of various sizes requiring minimal excavation. At 162,a breaking assembly is mounted (e.g., detachably coupled) to a firstbody. This may be accomplished in a number of ways. In one example, thebreaking assembly is detachably coupled to the first body using boltsand nuts. In another example, the breaking assembly is detachablycoupled to the first body using bolts and cotter pins.

At 164, the breaking assembly is detached from the first body. This maybe accomplished in a number of ways. In one example, the breakingassembly is detached from the first body by removing one or more nutsconnected to one or more bolts. In another example, the breakingassembly is detached from the first body by removing one or more cotterpins associated with one or more bolts.

At 166, the breaking assembly is mounted (e.g., detachably coupled) to asecond body. In various examples, a diameter associated with the secondbody differs from a diameter associated with the first body (notably, adiameter of the body typically relates to an inner diameter of theunderground pipe to be replaced, as discussed in greater detail above);however, the mounting of the breaking assembly to the second body maystill be accomplished in ways similar to the ways used in mounting thebreaking assembly to the first body. For instance, in one example, thebreaking assembly is detachably coupled to the second body using boltsand nuts. In another example, the breaking assembly is detachablycoupled to the second body using bolts and cotter pins.

Various options for the methods shown in FIG. 7 are possible. Forinstance, in one example, the breaking assembly includes one or morecutting wheels or scoring wheels rotatably coupled to a breakingassembly housing to split an existing underground pipe. In anotherexample, each cutting or scoring wheel is adapted to eccentrically mountto the breaking assembly housing at one or more positions. In anotherexample, at least one of the one or more cutting wheels or scoringwheels includes a notch at its periphery. In yet another example, one orboth of the first body and the second body include a shell structure. Ina further example, one or both of the first body and the second bodyinclude at least one skid structure coupled to an outer surface thereof.

At 168, a leading pulling device or a trailing pulling device is mountedto a first or second end, respectively, of one or both of: a first orsecond body and the breaking assembly housing. This may be accomplishedin a number of ways. In one example, the leading or trailing pullingdevice is detachably coupled to the breaking assembly housing bolts andnuts. In another example, the leading or trailing pulling device isdetachably coupled to the breaking assembly housing bolts and cotterpins. In another example, the leading or trailing pulling device ispermanently coupled to the breaking assembly housing. In varyingexamples, a size and shape of the leading or trailing pulling devicerelates to the size of the body used (e.g., the larger the body, thelarger the pulling device). In many examples, the leading pulling deviceincludes a bore to which a cable can be releasably engaged to pull theapparatus through the existing underground pipe. In many examples, thetrailing pulling device includes a bore to simultaneously pull areplacement pipe into place as the cable pulls the leading pullingdevice.

The present devices, apparatuses, and methods, as described above and asdefined in the appended claims, provide a number of advantages. Oneadvantage is the replacement of existing underground pipes requiringminimal excavation. Other advantages include the following. The use of aplurality of cutting or scoring wheels increasing in an amount eachwheel protrudes out of a breaking assembly housing from a first end to asecond end of one embodiment of the present apparatus allows for aclean, progressive cut of an existing pipe that provides consistency inthe split of the pipe, and reduces pulling force required in thesplitting operation. Another advantage includes cost savings through theuse of interchangeable bodies (e.g., shells) of varying sizes and anadaptive breaking assembly (e.g., adapted to be used with the pluralityof body sizes). Another advantage includes the use of skid structures,which are inexpensive to manufacture and help to reduce friction withthe existing underground pipe during a splitting or bursting operation.Yet another advantage includes the use of cutting or scoring wheelshaving one or more notches at their periphery. Such notches may providefor better wheel rotation, less drag, or increased cutting ability asone embodiment of the present apparatus is pulled through the existingunderground pipe. A further advantage provided by the designs disclosedherein is the ability to split corrugated steel pipe that previously wasnot splittable by trenchless methods. While a number of advantages ofthe present devices, apparatuses, and methods are herein described, theabove list is not intended to be exhaustive in any way.

As mentioned above, this Detailed Description is not to be taken in alimiting sense, and the scope of various embodiments is defined only bythe appended claims, along with the full range of legal equivalents towhich such claims are entitled.

In the appended claims, the terms “including” and “in which,” if used,are intended to mean the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Also, in the following claims, theterms “including” and “comprising” are open-ended, that is, a system,device, article, or process that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim. Moreover, in the following claims, the terms“first,” “second,” and “third,” etc. are used merely as labels, and arenot intended to impose numerical requirements on their objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus, the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

1. An apparatus for the trenchless replacement of an existingunderground pipe, the apparatus comprising: a body, including a pair ofbody portions including a receiving portion therebetween; and a breakingassembly, adapted to be inserted within the receiving portion anddetachably coupled to each of the body portions of the body, wherein thebody and the breaking assembly are adapted, when coupled, to break theexisting underground pipe when pulled therethrough.
 2. The apparatus asrecited in claim 1, wherein the breaking assembly is adapted to beinserted within the receiving portion of and detachably coupled to aplurality of differently-sized bodies.
 3. The apparatus as recited inclaim 1, wherein the breaking assembly includes one or more cuttingwheels, and wherein each cutting wheel is adapted to rotate relative toa breaking assembly housing.
 4. The apparatus as recited in claim 3,wherein the breaking assembly includes more than one cutting wheel, andwherein each cutting wheel radially protrudes out of the breakingassembly housing an increasing amount along a longitudinal length of thebreaking assembly housing.
 5. The apparatus as recited in claim 3,wherein each cutting wheel is adapted to eccentrically mount to thebreaking assembly housing at one or more positions, wherein each of thecutting wheels protrudes from the breaking assembly housing a differentdistance in each of the positions.
 6. The apparatus as recited in claim3, wherein the breaking assembly includes a scoring wheel, and whereinthe scoring wheel is positioned to score an inner surface of theexisting underground pipe in advance of the one or more cutting wheels.7. The apparatus as recited in claim 1, wherein the breaking assemblyincludes one or more cutting wheels, and wherein at least one of thecutting wheels includes a notch at its periphery.
 8. The apparatus asrecited in claim 7, wherein the body and the breaking assembly areadapted, when coupled, to break corrugated steel pipe when pulledtherethrough.
 9. The apparatus as recited in claim 1, furthercomprising: a leading pulling device, coupled to a first end of one orboth of: the body and the breaking assembly; and a trailing pullingdevice, coupled to a second end of one or both of: the body and thebreaking assembly.
 10. The apparatus as recited in claim 9, furthercomprising a cross bar, coupled to the leading pulling device on a crossbar first end and coupled to the trailing pulling device on a cross barsecond end.
 11. The apparatus as recited in claim 9, wherein the leadingpulling device is adapted to be pulled from an apparatus center.
 12. Theapparatus as recited in claim 9, wherein a size of the leading pullingdevice and a size of the trailing pulling device relate to a size of thebody.
 13. The apparatus as recited in claim 1, wherein the body portionsinclude substantially hollow shell structures, and wherein each of theshell structures includes at least one internal support member.
 14. Theapparatus as recited in claim 13, wherein the shell structures areadapted to receive, and detachably couple to, the breaking assembly. 15.The apparatus as recited in claim 1, further comprising at least oneskid structure, wherein each skid structure is coupled to an outersurface of the body.
 16. An apparatus for breaking an existingunderground pipe, the apparatus comprising: a body including a pair ofsubstantially hollow shells, including a receiving portion; a breakingassembly, adapted to be inserted within the receiving portion anddetachably coupled to the shells of the body; a leading pulling device,coupled to a first end of one or both of: the body and the breakingassembly; and a trailing pulling device, coupled to a second end of oneor both of: the body and the breaking assembly, wherein the breakingassembly includes one or more breaking elements protruding out of abreaking assembly housing.
 17. The apparatus as recited in claim 16,further comprising at least one skid structure, wherein each skidstructure is coupled to an outer surface of the body.
 18. The apparatusas recited in claim 16, wherein the one or more breaking elementsinclude a plurality of cutting wheels protruding radially outward fromthe breaking assembly housing.
 19. The apparatus as recited in claim 18,wherein each cutting wheel of the plurality of cutting wheels is adaptedto protrude out of the breaking assembly housing an increasing amountalong a longitudinal length of the breaking assembly housing.
 20. Theapparatus as recited in claim 16, wherein the one or more breakingelements include a fin.
 21. An assembly for use in an apparatus for thetrenchless replacement of an existing underground pipe, the assemblycomprising: a breaking assembly housing, adapted to detachably couple tothe apparatus; and one or more cutting wheels, each cutting wheeladapted to rotate relative to the breaking assembly housing, eachcutting wheel adapted to eccentrically mount to the breaking assemblyhousing at one or more positions, wherein each of the cutting wheelsprotrudes from the breaking assembly housing a different distance ineach of the positions; wherein the one or more cutting wheels arealigned along substantially one line of cut.
 22. The assembly as recitedin claim 21, wherein the assembly includes more than one cutting wheel,and wherein each cutting wheel is adapted to radially protrude out ofthe breaking assembly housing an increasing amount along a longitudinallength of the breaking assembly housing.
 23. The assembly as recited inclaim 21, wherein at least one of the one or more cutting wheelsincludes a notch at its periphery.
 24. The assembly as recited in claim21, further comprising a scoring wheel, adapted to score an innersurface of the existing underground pipe in advance of the one or morecutting wheels.
 25. A device for use in an apparatus for the trenchlessreplacement of an existing underground pipe, the device comprising: abody, including a pair of similar, semicylindrically-shaped bodyportions and a receiving portion adapted to detachably couple to abreaking assembly, wherein the body portions each include an internalsupport member disposed along an interior surface of each body portion;and at least one skid structure, coupled to an outer surface of thebody, wherein the body is adapted to detachably couple to the apparatus.26. The device as recited in claim 25, wherein the body portions includesubstantially hollow shell structures.
 27. A method for replacingexisting underground pipes of various diameters, the method comprising:mounting an interchangeable breaking assembly to a first body having afirst body diameter; detaching the interchangeable breaking assemblyfrom the first body; and mounting the interchangeable breaking assemblyto a second body having a second body diameter different than the firstbody diameter, wherein mounting the interchangeable breaking assembly tothe first body includes detachably coupling the interchangeable breakingassembly to the first body, and wherein mounting the interchangeablebreaking assembly to the second body includes detachably coupling theinterchangeable breaking assembly to the second body.
 28. The method asrecited in claim 27, wherein one or both of: the first body and thesecond body include a shell structure.
 29. The method as recited inclaim 27, wherein the interchangeable breaking assembly includes one ormore cutting wheels, and wherein each cutting wheel is adapted to rotaterelative to a breaking assembly housing.
 30. The method as recited inclaim 29, wherein each cutting wheel is adapted to eccentrically mountto the breaking assembly housing at one or more positions.
 31. Themethod as recited in claim 29, wherein at least one of the one or morecutting wheels includes a notch at its periphery.
 32. The method asrecited in claim 27, wherein one or both of the first body and thesecond body include at least one skid structure coupled to an outersurface thereof.
 33. The method as recited in claim 27, furthercomprising coupling a leading pulling device to a first end of one orboth of: the first or second body and the interchangeable breakingassembly.
 34. The method as recited in claim 27, further comprisingcoupling a trailing pulling device to a second end of one or both of:the first or second body and the interchangeable breaking assembly.